JPS5811716B2 - Test method and test device for magnetic bubble memory element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for testing magnetic bubble memory devices (hereinafter referred to as chips).

Generally, the above-mentioned chip has the configuration shown in FIG.

The arrow in the figure indicates the direction in which the bubble moves.

In the same figure, 21 is a bubble generator, and a bubble written by supplying a pulse current to this bubble is generated by an in-plane rotating magnetic field over a measure loop 22 formed by arranging transfer elements made of, for example, chevron battens. move in synchronization with the rotation of.

Next, this bubble is formed into a minor loop 29-3 by the gate circuits 23-27 and a gate pulse generator that causes a pulse current to flow through the conductor 20 of the gate circuits 23-27.
3 and is stored here.

Minor loop 2 when reading or writing bubbles
The information of 9 and 33 is passed through the gate circuits 23 to 27 with a pulse current from the gate pulse generator, and the measure loop 22
Then, from now on, it is moved on the major loop 22 to the plural erase circuit 34.

When reading, the information bubble is divided and duplicated by passing a duplication pulse current from the duplication erasing pulse generator to the duplication erasing circuit 34, and passes across the detection circuit to the detector 3.
Due to the magnetoresistive effect of 5, the resistance value of the detector 35 changes.

This change is converted into a voltage change, amplified by an amplifier (not shown), time sampled by a strobe pulse, and detected as a signal.

When erasing, the information bubble can be erased by passing an erasing pulse current from the replica erasing pulse generator through the conductor of the replica erasing circuit 34.

20a, 20b are pads for external connection of the gate circuit conductor 8; 21a, 21b are pads of the bubble duplication erasing circuit 34; 22a, 22b are pads of the bubble detector 35;
3a and 23b are pads of the bubble generator 1.

In reality, in addition to these parts, the chip also has minor loops 29 and 33 shown in FIG.
Since the outer circumferential conditions of the pattern are different from ~32, in order to align them, invalid loops called dummy loops that are not directly involved in memory are placed on the left side of minor loop 29 and 1 on the right side of 33.
Each loop is provided.

In addition, a pattern called a guardrail is formed to prevent storage bubbles from entering and leaving the wafer, and a space is provided between the chips on the wafer to allow for cutting lines for cutting into chips and to take into account blurring during cutting.

A plurality of chips having the above configuration are incorporated into the X and Y drive coils, and a large capacity magnetic bubble memory device can be constructed with this.

On the other hand, regarding the evaluation of the above-mentioned chip, it is necessary to know the operational margin of each function in high-speed operation, including slamming, evaluation, and process evaluation.

With the conventional method of determining the operating margin, it is impossible to measure the operating margin of each part at high speed in a state close to that of an actual magnetic bubble memory device.

The reason for this is that the read signal obtained from the detector 6 is compared with the write data to determine whether the operation is normal.

For example, in order to know the operating margin of only the minor loops 29 to 33, only a value including the operating margin of the major loop 22, the gate circuits 23 to 27, and the copy erase circuit 34 can be taken at the time of reading.

Therefore, an object of the present invention is to eliminate the above-mentioned drawbacks, and will be explained in detail below using examples.

FIG. 2 is an explanatory diagram showing an embodiment of the magnetic bubble memory element testing method and testing apparatus according to the present invention.

In the figure, 1 is a magnetic bubble memory element, 2 is a control unit, and the control unit 2 is connected to a rotating magnetic field control circuit 3. A signal is sent to the magnetic bubble memory element 1 via the XY drive 4 and the rotating magnetic field coil 5.
Further, signals are sent via various pulse generators 6, and signals are also sent to the magnetic bubble memory element 1 via a bias magnetic field control circuit 7 and a bias magnetic field generator 8.

The signal from the magnetic bubble memory element 1 is detected by a sense circuit 9, and the signal from this circuit 9 is read out.
D) Data 10 is sent to the control unit 2 via the error check circuit 11.

A signal is sent from the control unit 2 to the error check circuit 11 via the error check control circuit 12.

First, the operating margin of the major loop 22 is measured as follows.

In advance, a roughly appropriate bias magnetic field is set, then the control unit 2 is preset to major loop operation (hereinafter referred to as M operation), a write operation (Write operation, hereinafter referred to as WT) is performed, and then a read operation (Rea) is performed.
d operation (hereinafter referred to as RD) is continuously checked for errors, and if there is no error, the bias magnetic field is changed up and down to detect the upper and lower limits at which the error occurs.

The elements of the margin in this case are as follows.

Margeme N = Major loop transfer margin (transfer) 10 replication circuit operation (B) 10 detection circuit operation (to) Next, preset to M operation, and after WT, apply an in-plane rotating magnetic field to transfer the bubble, and then apply an in-plane rotating magnetic field to the optimum bias magnetic field. In R
Perform D operation and check for errors.

If there is no error, the RD operation is stopped again, an in-plane rotating magnetic field is applied, and the bias magnetic field is increased or decreased.

Thereafter, an RD operation is performed under the optimum bias magnetic field to check for errors.

This operation is repeated to determine the upper and lower limits of the bias magnetic field for normal operation.

The elements of the margin in this case are as follows.

Margin (B) = Major loop transfer margin (M) Next, preset M operation and repeat WT-RD (WT at this time means rewrite operation) while changing the bias margin to ensure normal operation. Know the upper and lower limits of the bias magnetic field.

The elements of the margin at this time are as follows.

Margin (c) - Bubble generator (D) + M + R + D Next, the control unit is preset to M/m operation (major/minor loop operation).

After performing WT with the optimum bias magnetic field, that is, after moving the written information to the minor loop, the RD and WT operations are stopped and only the in-plane rotating magnetic field is activated.

In this state, the bubbles on the minor loops 29 to 33 simply rotate within each minor loop many times.

Thereafter, an RD operation is performed in the optimum bias magnetic field to perform an error check.

If there is no error, the RD operation is stopped again.

At this time, the bubble information has already been stored in the minor loop.

While the bubble is transferred in the minor loop, the bias magnetic field is changed slightly, and after a while, it is returned to the original optimum bias magnetic field, and RD operation and error check are performed.

In this way, the upper and lower limits of the bias magnetic field that normally moves within the minor loop can be known.

The elements of the margin at this time are as follows.

Margin (D) Minor loop transfer margin (m)
Next, preset to M/m operation as the most common margin and repeat the RD-WT operation to find the limit of the bias magnetic field that does not cause an error.

The margin at this time is as follows.

Margin (e) - G+R+D+M+m+Gate circuit margin (Gate) Based on the five types of margins obtained as described above, the following operating margins can be obtained.

Major loop transfer only = (B) = M Minor loop transfer only = (D) = m Replication circuit + detection circuit = (a) - (B) = R + D generation circuit = (C) - (a) = G Gate circuit - (e) - (C) - (D) = Gate As explained above, according to the present invention, it is possible to measure the margin for each part side, and this can be done automatically by assembling the circuit shown in the block diagram of Fig. 2. This makes it possible to have a beneficial effect on the evaluation of pattern film materials and processes.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing an example of a magnetic bubble memory element, and FIG. 2 is a block diagram for explaining an embodiment of a magnetic bubble memory element testing method and testing apparatus according to the present invention. DESCRIPTION OF SYMBOLS 1... Magnetic bubble memory element, 2... Control unit, 3... Rotating magnetic field control circuit, 4... XY coil drive circuit, 5... XY coil for rotating magnetic field, 6...
・Various pulse generators, 7...bias magnetic field control circuit,
8... Bias magnetic field generator, 9... Sense circuit, 1
0...RD data, 11...Error check circuit,
12...Error check control circuit.

Claims (1)

[Scope of Claims] 1. In a method for testing a magnetic bubble storage element alone or a storage element incorporated in a device, in order to determine a partial bias magnetic field margin of the magnetic bubble storage element, magnetic bubble transfer of the portion to be determined is performed. A test method for a magnetic bubble memory element in which the magnetic bubble memory element is operated with the optimum bias magnetic field margin except for the operation, and the bias magnetic field is supplied only during the operation of this section to determine the upper and lower limit values of the bias magnetic field at which this section operates normally. . 2. A bias magnetic field control circuit that controls a bias magnetic field supplied to the magnetic bubble storage element, a drive coil that supplies an in-plane rotating magnetic field to the magnetic bubble storage element, and an error check for data read from the magnetic bubble storage element. 1. A testing device for a magnetic bubble memory element, comprising: an error check circuit for performing a test, and an error check control circuit for controlling a check level of the error check circuit.